In an exemplary drive system for a vehicle, there usually is a power supply, an output mechanism, a power coupling system, and a housing and/or structural apparatus. The power supply typically is an engine or a motor, although other means also may be employed. The output mechanism converts power received from the power supply to motive force for the purpose of moving and directing the vehicle. In a boat, the output mechanism typically is a propeller. The power coupling mechanism couples, transmits or transfers power from the power supply to the output mechanism. Often the power coupling system includes one or more of a drive shaft, an output shaft, other coupling gears and shafts, a clutch, a transmission, etc. The housing and/or structural support apparatus typically holds one or more of the other components of the drive system in relation to each other in order to accomplish the appropriate interaction to effect the desired driving function. Additionally, the housing and/or structural support mechanism may provide, to the extent needed and/or desired, appropriate enclosure functions.
The present invention preferably relates to drive systems for boats. As it is used herein, the term "boat" is intended to mean virtually any type of water craft, vehicle, apparatus, device, etc., that is intended to be operated on, in and/or under water. The features of the present invention are particularly useful with surface craft, i.e., boats that float and/or are operated at the water surface, and especially drive systems therefor that are rated at from about 100 horsepower up to about 1000 horsepower and beyond 1000 horsepower, and especially in the range of from about 100 hp to about 250 hp. However, it will be appreciated that features of the invention may be used with other boat drive systems and at other power levels, e.g., those that are rated at less than 100 horsepower or more than several hundred horsepower, or even more than 1,000 horsepower, depending on the sizes of the several components of the outdrive.
Moreover, although the features of the present invention are particularly useful in and relate to boat drive systems, it will be appreciated, and it is intended, that features of the invention may be used in drive systems for vehicles other than boats and/or in other applications, too. For compactness, though, the following description is directed to application of the features of the invention in drive systems for boats; application of features of the invention in other drive systems will be evident to those having ordinary skill in the art in view of the disclosure hereof.
Conventional boat drive systems often are categorized by labels inboard, outboard, and inboard/outboard. In an exemplary inboard drive system the power supply, which will be referred to hereinafter for convenience as an engine although it may be a motor or some other source of power, and the majority of the power coupling system are located within the boat, which provides at least some housing and structural support functions. The propeller and at least part of the propeller shaft, of course, are located outside the boat in the water, as also is the case for outboard and inboard/outboard drive systems. One example of an inboard drive system is an in line system in which the engine, clutch, transmission and propeller shaft generally are in line facing from the front to the back of the boat, the propeller being at or near the back. Another example of an inboard drive system is referred to as a V-drive. In an outboard drive system typically the engine and the power coupling system are located outside or mostly outside the boat. Furthermore, in an inboard/outboard drive system an exemplary configuration employs an engine located in the boat and a power coupling system that has a substantial portion located outside the boat. The foregoing is exemplary; it will be appreciated that various hybrid combinations of the foregoing categories of boat drive systems, as well as other types of boat drive systems also exist and/or may exist in the future.
The present invention includes features that may be useful in the various categories or types of boat drive systems mentioned above and in others that may not be specifically identified. However, according to the preferred embodiment and best mode, as is described in greater detail below, the present invention has particular utility when employed in and/or with the outdrive portion of the power coupling system of an inboard/outboard boat drive system and of outboard boat drive systems. Features of the invention also are especially useful in V-drive systems.
The term outdrive typically means that portion of a vehicle drive system, usually excluding the engine, which is located outside the hull of a boat. The outdrive usually is part of or is the entire power coupling system of a boat drive system and also may include the output mechanism, typically the propeller. As they are used herein, the terms outdrive and power coupling system may be used synonymously, and such terms also may be used to designate non-overlapping parts or functions, i.e., not synonymously; the context will make the usage clear. For example, the engine drive shaft itself may be considered part of the power coupling mechanism, as is the universal joint, but only the latter usually would be considered part of the outdrive.
In a conventional outdrive type of power coupling system, power is coupled between the engine and the output mechanism, which for convenience is referred to below as the propeller. Typically during use, the engine drive shaft or at least the power input shaft for the outdrive and the propeller shaft are oriented generally in parallel horizontal directions and are vertically spaced apart. The conventional outdrive includes a rigid coupling shaft and associated gears to couple the rotary output from the drive shaft to the propeller shaft. Accurate positioning of the various parts of such a conventional outdrive is necessary in order to assure proper alignment and meshing of respective gears and shafts, as is well known. Relatively rigid metal castings typically are used as housings for such outdrives to provide the necessary stiffness to obtain the necessary accurate positioning functions mentioned.
The gears, coupling shaft, and metal castings employed as housings and/or other parts for such conventional outdrives are relatively expensive to manufacture and are relatively heavy. It would be desirable to reduce the expense of manufacturing an outdrive.
The gears and coupling shafts of such conventional outdrives are usually located in an oil filled chamber. The oil provides usual lubricating function. Heat developed by the rotating gears and shafts heats the oil, which is cooled by thermal conduction through the metal housing of the outdrive to the water in which the outdrive, and indeed the boat, are immersed.
An outdrive usually is mounted on a pivot housing and/or gimbal ring to allow for steering, trimming (e.g., thrust angle), and tilt (e.g., for storage).
One example of an outdrive which uses a flexible power coupling member in the form of a belt is disclosed in Dunlap U.S. Pat. No. 3,951,096. Such outdrive has a metal housing with two separate hollow down legs to enclose the two respective legs of the belt. Such hollow down legs extend between the upper housing portion where a drive sprocket is located and the lower housing portion (sometimes referred to as the torpedo) where a driven sprocket is located. The driven sprocket is coupled to the propeller. The present invention includes a number of improvements that may be employed with such a belt driven outdrive.
Outdrives have included kickup features so that the outdrive kicks up or tilts out of the way when it strikes an object, such as a log, rock, lake bottom, etc. to avoid damages to the outdrive and/or other parts of the drive system or boat. Usually hydraulic cylinders having high pressure hydraulic fluid therein hold the outdrive, especially the propeller, at a particular trim angle to obtain a particular thrust angle for desired boat operation. If the outdrive strikes an object, hydraulic fluid in such cylinders is forced through small orifices to allow the outdrive to kickup out of the way of such object. The speed with which the fluid flows is a function of orifice size and fluid pressure, which in turn is a function of the force applied to the outdrive by the object struck.
U.S. Pat. No. 5,178,566, which is incorporated entirely by this reference, discloses an outdrive using a non-metal housing and a belt to couple power between the input and output. It has been found that energy losses may occur due to vortices generated within the oil between the belt legs and/or other unnecessary oil pumping actions. It would be desirable to reduce such losses. It also was found that belt tensioning sometimes was difficult; it would be desirable to improve belt tensioning techniques. It also was found that improved heat removal techniques would be advantageous.
Several other improvements to outdrives, such as the outdrive described in the '566 patent and other outdrives, also would be advantageous and are disclosed herein.